Ingredients
Scale
For the vanilla-chocolate cake layers
- 3 cups (360 g) all-purpose flour
- 2½ teaspoons baking powder
- ½ teaspoon fine salt
- 1 cup (226 g) unsalted butter, softened
- 1¾ cups (350 g) granulated sugar
- 4 large eggs, room temperature
- 1 tablespoon vanilla extract
- 1¼ cups (300 ml) whole milk, room temperature
- ⅓ cup (28 g) unsweetened cocoa powder
- 2 tablespoons whole milk, reserved for the chocolate batter
For the vanilla buttercream
- 1½ cups (340 g) unsalted butter, softened
- 5 cups (600 g) powdered sugar, sifted
- 2 teaspoons vanilla extract
- 3–5 tablespoons heavy cream
- ⅛ teaspoon fine salt
For the milk chocolate ganache
- 8 oz (226 g) milk chocolate, finely chopped
- ¾ cup (180 ml) heavy cream
For decorating
- Broken milk or dark chocolate bars
- Chocolate wafer cookies
- Chocolate-covered wafer sticks
- Chocolate truffles
- Mini chocolate-glazed donuts
Instructions
- Prepare the oven and pans. Preheat the oven to 350°F (175°C). Grease three 8-inch round cake pans. Line the bottoms with parchment circles and lightly grease the parchment.
- Combine the dry ingredients. Whisk the flour, baking powder, and salt in a medium bowl.
- Cream the butter and sugar. Beat softened butter and granulated sugar for 3–4 minutes, until pale and fluffy.
- Add the eggs. Beat in the eggs one at a time. Let each egg mix in before adding the next. Scrape down the bowl when needed. Mix in the vanilla.
- Finish the vanilla batter. On low speed, alternate the flour mixture with the 1¼ cups milk. Begin and finish with flour. Mix only until combined.
- Make the chocolate batter. Transfer about one-third of the batter to another bowl. Sift in the cocoa powder. Fold in the reserved 2 tablespoons milk until smooth.
- Create the marble layers. Divide the vanilla batter between the three pans. Spoon chocolate batter over each portion. Make a few broad swirls with a knife or skewer. Do not over-swirl.
- Bake. Bake for 25–30 minutes. Begin checking at 25 minutes. A toothpick inserted near the center should come out clean or with a few moist crumbs.
- Cool. Leave the cakes in their pans for about 10 minutes. Turn onto wire racks, remove the parchment, and cool completely.
- Make the buttercream. Beat the butter for about 3 minutes. Gradually beat in the powdered sugar. Add vanilla, salt, and 3 tablespoons heavy cream. Beat until light and creamy. Add more cream, one teaspoon at a time, only if needed.
- Stack the cake. Level cooled layers if necessary. Put the first layer on the cake board. Spread about ¾ cup buttercream over it. Repeat with the second layer. Add the final layer upside down for a flatter top.
- Crumb coat. Cover the entire cake with a thin coat of buttercream. Refrigerate for 20–30 minutes.
- Final coat. Cover the chilled cake with the remaining buttercream. Smooth the sides while keeping the tall cylindrical appearance. Chill for another 20–30 minutes.
- Make the ganache. Put finely chopped milk chocolate in a heatproof bowl. Heat the cream until steaming but not vigorously boiling. Pour it over the chocolate and wait 2–3 minutes. Stir gently until glossy.
- Test the drip. Allow the ganache to cool until it falls slowly from a spoon. Test one drip on the back of the cold cake. It should travel partway down the side rather than reaching the cake board immediately.
- Decorate. Add ganache around the rim and spread some across the top. Arrange broken chocolate bars, wafer cookies, wafer sticks, truffles, chocolate pieces, and mini chocolate-glazed donuts in a loose cluster across the top.
- Set and serve. Let the finished cake settle before cutting. For cleaner slices, use a sharp knife warmed with hot water and wiped dry between cuts.
Notes
- Do not skip the extra 2 tablespoons of milk in the cocoa portion. Cocoa absorbs moisture, and this small addition helps the chocolate sections remain closer in texture to the vanilla cake.
- Use room-temperature eggs, milk, and butter for smoother batter.
- Weighing the flour is preferable. Use 360 g when possible.
- Do not overmix after adding flour.
- Do not frost warm cake layers.
- Chill the buttercream-covered cake before adding ganache.
- Always make one test drip at the back before decorating the visible sides.
- If the ganache races downward, it is too warm. Wait a few minutes.
- If it barely moves, gently warm it again.
- Add the largest chocolate decorations first.
- Add wafer decorations relatively close to serving time if you want them crisp.
- Exact decoration quantities are intentionally flexible because chocolate bars, wafers, truffles, and mini donuts differ greatly in size.
- Prep Time: 1 hour 10 minutes
- Additional/Chilling Time: 50 minutes
- Cook Time: 25–30 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American-style
